This invention relates to machine-readable records and, more particularly, to a novel and highly-effective mark-sense card including a selectively-activated operator that may be preprinted on the card and that greatly increases the amount of information that the card is capable of recording. The invention relates also to apparatus for, and a method of, reading and interpreting the card.
Conventional machine-readable records such as mark-sense cards typically comprise a plurality of indicia, usually alphameric characters, different ones of which can be selectively activated as by marking with a writing implement and, when so activated, are interpreted in a manner that is both conventional and unique. The interpretation is unique in the sense that each set of marked or otherwise activated alphameric characters has one and only one interpretation. This constraint limits the amount of information that can be recorded on the card or other record. More information can be compressed onto the card only by making the individual indicia smaller or placing them closer together. This makes both the marking and the reading and interpretation more difficult and subject to error.
The art of designing and reading mark-sense cards is well developed. A British Pat. No. 817,902 discloses a system for marking and sensing alphameric characters wherein characters are selectively activated by placing marks in separate tracks adjacent to the visually-readable characters. A U.S. Pat. to Bijleveld et al No. 3,527,927 discloses a system for marking numbers which is said to overcome certain drawbacks of the system disclosed in the British patent. The system disclosed in the British patent is susceptible to human errors. The system disclosed in the U.S. patent is intended for general use by a "heterogeneous public" and, in addition to being more closely adapted to the natural writing habits of the public, offers a "self-checking" feature. Each "cipher" or numeral is merely written into a box assigned to that numeral at a position visibly indicated within the box. The absence of a numeral is indicated by striking out or cancelling the cipher indication. A U.S. Pat. to Lee No. 3,626,368 discloses a character-reading machine which includes circuitry that is more sophisticated than that necessary for reading mark-sense cards in which the location, as opposed to the configuration, of a stroke made by a writing implement determines the identity of a character. In all of the prior art, the information that can be recorded on a mark-sense card is severely limited.